Apparatus and process for cutting back pitch



July 11, 1933. G. E. MCCLOSKEY APPARATUS AND PROCESS FOR CUTTING BACKPITCH Filed July 51, 1929 3 Sheets-Sheet 1 Ti u u I M u u u" n n n U u Hu H H n I u H H u n H u H n. v u

I: H D .1? U.

INVENTOR ATTORNEYS July 1 1, 1933. G. E. McCLOSKEY APPARATUS AND PROCESSFOR CUTTING BACK PITCH Filed July 31, 1929 3 Sheets-Sheet 2 ATTORNEYSJuly 11, 1933. E MCCLOSKEY 1,917,384

APPARATUS AND PROCESS FOR CUTTING BACK PITCH Filed July5l, 1929 sSheets-Sheet 5 ja C If 7 V LLB fi/ z/flj I eme/ INLENTOR 77 2 Q G m/qATTORNEYS Patented July 11, 193 3 UNITED STATES,

PATENT OFFICE GREGORY EDWARD MCCLOSKEY, OF SOUTH ORANGE, NEW JERSEY,ASSIGNOR THE BARRETT COMPANY, OF NEW YORK, N Y., A CORPORATION OF NEWJERSEY APPARATUS AND PROCESS FOR CUTTING BACK PITCH Application filedJuly 31,

This invention relates to the mixing of hot thinly fluid pitches of highmelting point and hydrocarbon fluxes of lower melting point, for exampletars or semi-pitches, to form homogeneous mixtures herein referred to asblended pitches. More particularly the invention relates to theproduction of blended pitches by mixing pitches of high melting point,e. g. 300 F. or 400 F. or higher, made by distilling tar by directcontact with hot coke oven gases, with a flux which is a semi-pitchprepared by stripping tar, preferably the same tar from which the highmelting point pitch is prepared, to remove only its lower boilingconstituents. The invention includes both the method and apparatus forcarrying it out.

In blending a high melting point pitch or (N pitchy mixture while hotand fluid, herein referred to as a base, with a flux, which may be a caror semi-pitch and which may be cold or heated somewhat, care must betaken to blend the hot base thoroughly with the flux before the base orany portion of it has cooled to a point where the base congeals andforms masses which will not readily blend further with the flux. coolsbefore being blended with the flux it may settle out from the flux ashard pitch, or it may form a gelatinous mass known in the art as liver.When once the base has separated from the flux in either form, it isdifiicult and expensive to treat the mixture further to form ahomogeneous blended mixture.

Processes which involve heating the flux to a high temperature to causeit to blend with the hot base involve high heat costs. Furthermore,heating the flux to a temperature at which satisfactory blending couldbeeffected in an ordinary mixing tank is usually not practicable. Suchhigh heat costs as well as other difficulties in blending may beeliminated according to this invention since the base may be blendedwith the flux while in its initial hot fluid condition in which it isformed, and the flux, if employed in small amounts, may be used cold. Ifthe flux is to be used in large proportions it may be desirable to heatit somewhat. In any case, the

If the base 1929. Serial No. 382,375.

preferably washed with a layer of the flux.

The base is added to the vessel in such a manner that it does not comeinto contact with the fresh flux employed for washing the walls of thevessel but is brought into contact with a body of the blended materialmaintainedwithin the vessel, and this blended material is sprayed oragitated to cause incorporation of the hot pitch without the formationof liver or hard itch. The end-productis preferably with rawn from thevessel in a continuous stream.

The pitch base is added to the vessel in such a way that it is notchilled by contact with the outside walls of the vessel and does notharden and build up a deposit of hard pitch base on the walls of thevessel. On the other hand, the incoming flux continuously washes downthe walls, keeping them free from deposits of material of'high meltingpoint not yet uniformly mixed with the mass of blended material. Theflux is thus gradually'added to the of blended material in the form of athin'sheet which runs down the walls of the vessel and blends with thecut-back material within the vessel. The flux is added at the peripheryof the mass of cut-back material and the base is added within theperiphery of the mass of cut back material. Stirring or agitating meansare provided within the vessel and foam breakers are also advantageouslyemployed to break the foam caused by blending the hot pitch with flux,which may contain some moisture.

Vapors distilled from the flux during the blending operation may bedrawn ofi from the vessel and condensed to form a separate distillateproduct, or the condensate may be returned to the blending vessel.

The base may be a high melting point pitch such as a pitch with amelting point of 300 F. or 400 F. or even higher. It may be a pitchformed by the distillation of tar with hot coke oven gases and theinvention may advantageously be carried out in conjunc= tion with such adistillation process to pr0- duce a blended product of desiredproperties, but the invention is not limited to that process alone.

The fiux may be an oil, tar or a partially distilled tar, i. e. asemi-pitch. It may be heavy tar from the collector main of a coke ovenplant or the hydraulic main of a retort plant, or a lighter tar such asthe tarry oils from the condensers of such plants; It may be gashousetar, water gas tar, etc. i The flux may be a dehydrated tar or raw tar,i. e. tar containing a small percentage of water. A -mixture of any ofthese materials may be employed as the flux. The base is employed in ahot thinly fluid state, preferably as it comes from the still in whichit is produced, although the base may be prepared for use by melting apitch which has been allowed to harden. The flux may be preheated to agreater or less extent, al-

though it may be blended cold. Where a large amount of flux is to beblended with a smaller amount of pitch, preheating of the flux may bedesirable to allow incorporation of a larger amount of the flux with thepitch without causing the base to separate from the blended material.Although the invention will be described in the drawings moreparticularly as ap- :plied in connection with the operation of a stillin which tar is distilled by direct con- --tact with hot coke ovengases, it is to be understood that the invention is not limited toblending a flux with a base from this source. The base may be pitchprepared by the distillation of tar by any of the methods well known tothose skilled in the art.

In the drawings,

Fig. 1 is a plan view of a coke oven plant equipped'with a still for thedistillation of "tar to produce a suitable base and showing the blendingvessel of this invention for blending the base with a flux.

Fig. 2 is an elevation partly in section of the apparatus of Fig. 1;

Fig. 3 is a section through the still;

Fig. 4 is an enlarged view showing a crosssection through the blendingvessel; and

Fig. 5 is a plan view of the blending vessel.

'In the drawings, 5 indicates a coke-oven battery connected in the usualway through uptake pipes 6 with a collector main 7. The cross-over main8 leads from the centerbox 9 of the collector main to condensers andmeans for'the recovery of ammonia, etc. This apparatus may be of theusual type and is shown enses ployed for the blending operation of thisinvention. The tar may be coke oven tar, gashouse tar or other tar andit is distilled to a high melting point pitch, and the pitch is employedas the base for blending with a suitable flux.

In the drawings, the still 10 is equipped with a roll 11 connected witha motor 12 which is adapted to rotate the roll 11 at high speed, e. g.900-1200 r. p. m., and thus produce a fine spray of tar within the still10. Selected ovens of the battery are equipped with uptake pipes 13 atthe opposite end of the ovens from the uptake pipes 6. These uptakepipes lead into the hot gas header 14. Valves 15 are provided in theuptake pipes 13 and by proper manipulation of these valves and valves ofthe usual type in the uptake pipes 6, the hot gases from these selectedovens may be passed either to the collector main 7 or through the hotgas header 14 into the still 10. The uptake pipes 13, the header 14, thestill 10, and also the tower 17 are heavily insulated as indicated at16.

A small body of the tar or low melting point pitch which is beingdistilled is kept within the bottom of the still. By rapid rotation ofthe roll 11, this tar or pitch is thrown up into the hot gases admittedfrom the header 14 and brought into direct contact with these hot gasesin the form of an intense spray. The tar or pitch is distilled by thehot gases and the hot gases are substantially de tarred. Tar fogcomprising particles of coke, dust, pitch, etc., entrained in the gasesleaving the ovens is removed from the gases by this fine spray of thematerial being dis tilled. The gases leavin the still are sub-"stantially de-tarred an clean oils.

The gases leave the still through the settling tower 17 where any smallpart of the spray which may be entrained in the gases is separated fromthe gases either by gravity or by the tar which is sprayed into thegases passing up through this tower. The tar to be distilled is admittedto the tower through the line 18 and the nozzle 19. A bafiie 20 formedof Raschig rings is provided below the tar spray to expose a largesurface of the incoming tar to contact with the hot gases to causevaporization of lower boiling constituents of the tar, and also to washout particles of the spray produced in the still 10, which may becarried from the still by the gases. Above the spray 19 another bafile21 is shown for removing from the gases any particles of spray which maybe carried up through the tower beyond the spray 19.

' In order to produce a high melting point pitch it is desirable to passthe hot gases and the tar or pitch through the still in a concurrentdirection so that the incoming tar or semi-pitch comes in contact withthe hot gases and the partially distilled material or nearly on coolingyield pitch and the formation of coke on these walls,

In order to provide for concurrent flow of the gases and pitch throughthe still, the

partially distilled tar or semi-pitch which collects in the bottom ofthe tower 17 is prevented from flowing down through the passage 23through which the gases pass from the still into the tower, and it isdrawn off through the line 24 and admitted to the still at the end ofthe still at which the hot gases enter through the hot gas header 14.

The hot cleaned gases enriched in oil vapors leaving the top of thetower 17 are cooled in any suitable manner to recover clean oilproducts. The condensers 25 are here shown for that purpose. These aredirect condensers in which the gases are sprayed with ammonia liquorfrom the lines 26.

The condensate is collected together with ammonia liquor in one or moredecanters 27. From these decanters the clean oil is separately collectedin one or more tanks such as those shown at 28. Beyond the condensers anexhauster 29 and means for the recovery of ammonia and light oils, etc.from the gas is provided.

The pitch is withdrawn from the still 10 through the coke trap 30 inwhich any coke which may form in the still is separated from the pitch.The pitch is withdrawn from this coke trap through the levelling arm 31.By regulating the position of this levelling arm the depth of the tar orpitch in the bottom of the still is controlled and this automaticallycontrols the nature of the spray 'thrown from the roll. The levellingarm may discharge into a trough 32 in which the hot pitch is instantlychilled by a stream of cold water from the line 33 which granulates thepitch. After being chilled in this manner the'pitch may be collected ina storage bin 34.

\Vhen the pitch is to be employed in the blending operation of thisinvention, the levelling arm 31 is thrown over so that the pitch isdischarged into thecup 36. This cup may be situated on the outside ofthe blending vessel 37 or the pitch may be piped from this cup to theblending vessel- The blending vessel 37 is preferably a cylindricalvessel. The enclosing wall 38 may be a section cut from twelve inch pipeand may be some fifteen inches high, although the size of the vessel mayvary depending upon the quantity of material to be handled. From the cup36 the pitch is admitted into the body of the vessel in such a way thatit does not come in contact with the containing wall of the vessel, andthe pitch flowing into the vessel is advantageously protected by abaflie to'prevent the incoming fl'uxfrom' being sprayed into thepitch'as it enters the vessel. The spout 39 prevents the pitch fromtouching the wall 38 and hardening and building up on this wall and thebaflle 40 shields incoming pitch from the spray of flux, describedbelow. In order to prevent the escape of vapors through the pitch inlet,another baflie 41 is provided which dips into the pitch contained'withinthe cup 36.

The shaft42 resting in the bearing 43 is positioned vertically in thecenter of the blending vessel. It passes through the cover 44 of thevessel through a suitable stuffing box 45. A pulley 46 is provided torotefte this shaft 42 at high speed.

In the upper part of the vessel is the disc 47 which is fastened to theshaft .42 and rotates with it. The flux to be blended with the pitch isadmitted to the vessel through the pipe 48. The flow of flux iscontrolled by the valve 49. The flux as it enters the chamber falls onto the disc 47 and because of the high speed of rotation of this discthe flux is thrown by centrifugal force out against the walls of thevessel and forms a continuous sheet of fresh flux on all of the walls,washe ing them and keeping them clean and preventing the accumulation onthe walls of any material thrown up'onto the walls from the mixingoperation carried on within the vessel. The bafile 40 shields the pitchinlet and prevents the fresh flux from being brought into contact withthe pitch before it enters the vessel.

The incoming flux washes down the walls of the vessel and blends withthe pitch and a small body of the blended and blending ma terial whichis maintained within the vessel at all times.

provided in the draw-ofl line 54 to serve as a' sight-hole to observethe flow of blended material through this line.

This body of material is agitated or stirred by suitable means such asThe stirring arm 50 imparts a swirling motion to the body of materialwithin the vessel. The flux is added at the periphery of this body ofmaterial, continuously, and in the form of a thin sheet. The incomingpitch falls within the periphery of the body of blended and blendingmaterial in the vessel and blends therewith. The flux, continuouslyadded at the periphery of the body of blended and blending flux andbase, rapidly blends therewith, as does the base, added Within theperiphery of this body of material. The material formed by this separateblending of the fiuxand base with the body of blended and blendingmaterial in the vessel is homogeneous.

If the flux contains moisture itis vaporized on blending with the hotbase and may cause foaming. Any foam formed within the vessel is brokenup by the foam breakers 55;. Vapors escaping from the blending vesselmay be passed ofl into the atmosphere through the vent 56, or they maybe condensed and returned to the vessel or separately collected. Thevent 56 may be connected with the still so that vapors escaping 140 145F. B.) by blending pitch with a melting point of about 400 F. (A. B.)from the still 10, with semi-pitch of a melting point of about 100 F.(W. B.) I have found that by rotating the shaft 42 at a rate of 400- 450R. P. M. adequate agitation of the contents of the vessel is provided,the flux is well distributed on the walls of the vessel and theformation of an excessive foam layer is prevented when only one foambreaker is employed.

In blending a high melting point pitch produced by the distillation oftar with hot coal distillation gases, the flux may be supplied to theblending vessel through the pipe 60 and the flux feed 48. Where asemi-pitch, i. e. a partially-distilled tar, is to'be used and this is asemi-pitch produced from the same tar that the base is formed from, theoperation may be so controlled that the semi-pitch is produced withinthe tower 17. The partially distilled tar drawn off from the bottom ofthe tower may entirely or in part flow through the line 24 into thestill 10 and part may be drawn oil through the line 61 and be admittedtothe blending vessel as flux through 48. If all the semi-pitch formed inthe tower 17 is used in the blending operation, tar from some othersource is fed to the still 10 through pipe 24. By f drawing oflt'semipitch front the tower directly into the blendmg vessel thesemi-pitch is used in a hot or warm condition and the warm flux may beadded to the hot pitch in relatively large amounts without difliculty.

The operation is not limited to the utilization of a 'flux produced inthis distilling operation, but flux from another source may be admittedto the blending vessel through the line 60.

To produce a roofing pitch, as in the example given, the high meltingpoint pitch is supplied directly from the still to the blending vessel.Tar, which may be ordinary coke oven tar, is admitted to the distillingapparatus through the line 18. It 7 passes down through the tower overthe baifle 20. It is partially distilled by the hot gases and vaporsfrom the still. A portion of the semipitch thus produced enters thestill proper through the line 24. The hot coke oven gases from theheader 14 pass through the still and the tar, on being brought intointimate contact with these hot gases is distilled. The

operation is so regulated that a pitch of 400 F. is produced. This pitchis drawn ofi' continuously from the still through the coke trap into thecup 36 and admitted to the blending vessel through the spout 39.Semi-pitch also from the bottom of the tower enters the blending vesselthrough the lines 61 and 48. In starting the operation, the flux, i. e.,the semi-pitch, is admitted gradually to the blending vessel, the amountbeing controlled by the valve 49. The agitator is'set in motion. Byobserving the draw-off through the sight-hole 53, one can readilydetermine when a small stream of the flux is being drawn off at 54, i.e. when the blending vessel contains sufficient flux to function underoperating conditions The levelling arm 31 through which the pitchescapes from the still is then thrown from the position in which itdischarges into the trough 32 to the position shown in the drawings, sothat the pitch now enters the cup 36 and flows thence into the blendingvessel. The pitch enters the vessel without touching the walls and isblended into the body of material maintained within the vessel. Theflux, i. e. the semi-pitch, is sprayed on to the walls of the vessel,continuously washing them, ai rd thus continuously blends with the bodyof material within the vessel. The amount of pitch and flux are soproportioned that the desired product is obtained. In producing roofingpitch, for example, 42.545 volumes of base may be blended with 57 .5-55volumes of flux, according to the method, and in the apparatus, heredescribed. Vapors produced during the operacontinuously adding flux tothe body at a pluralityof widely separated points without' firstbringing the flux into direct contact with and then blending the pitchwith the balance of the semi-pitch by bringing the pitch in a hot thinlyfiuid condition direct from the still into contact with the semi-pitchwith agitation to insure the formation of a homogeneous blended product.

3. The method of producing blended pitch products from tar at a coaldistillation plant, which comprises distilling the tar to semipitch,.distilling a portion of the semi-pitch to pitch with a melting point ofat least 300 F. in a second distilling operation by bring- L ing thissemi-pitch into direct contact with hot coal distillation gases in theform of an intense spray, utilizing the hot. gases and vapors from thisdistillation to distill the tar to semi-pitch, continuously blending thepitch while still hot and thinly fiuid by blending it with the balanceof the semi-pitch, and adding the semi-pitch to the pitch by spraying itonto the walls of the blending vessel while stirring the contents of thevessel and continuously drawing off the blended product.

4. In combination with means for distillingtar with hot gases in twostages, a still, a saturator,-means for continuously passing hot gasesthru the still and then thru the saturator, means for continuouslyintroducing tar to the saturator, a blending vessel, means for drawingoff a portion of the residue from the saturator to the blending vesseland for introducing the balance of the residue into the still, means fordrawing ofi pitch from the still and introducing it into the blendingvessel, agitating means in the vessel to blend the pitch and residue,and means for continuously removing the blended product from i theblendin g vessel.

51 The method of producing blended pitch products from tar, whichcomprises distilling the tar to semi-pitch, distilling a portion of thesemi-pitch to pitch with a high melting point and then blending thepitch of high melting pointwith the balance of the semipitch by bringingthe pitch in a hot thinly fluid condition directly from the still intocontact with the semi-pitch while agitating to insure the formation of ahomogeneous blended product. g

6. The method of producing blended pitch products from tar, whichcomprises passing fresh hot gases through two stills in series, bringingtar intocontact with the gases in the second still, thereby vaporizingconstituents of the tar, bringing a portion of the treated tar from thisstill into contact with the gases in the first still in the form of afineintense spray, whereby the tar is further distilled and the gasesare cooled, and blending at least a portion of the product resultingfrom the distillation in the second still with at lealslt a part of thetreated tar from the first sti 7. The method of producing blended pitchproducts. which comprises passing hot gases through two stills inseries, bringing tar into contact with the gases in the second still soas to volatilize lower boiling constituents from the tar, distilling taror pitch in the first still by spraying it into the gases in the form ofa fine intense spray and blending pitch produced in the first still withtreated tar from the second still.

8. Apparatus for producing blended pitch products, which comprises twostills, means for passing hot gases through the first still and thenthrough the second still in series, means for introducing tar into thesecond still, means for withdrawing residue from the second still anddividing it and conveying part of the residue to the first still, ablending tank, means for conveying a part of the residue from the secondstill to the blending tank, means for conveying residue from the firststill to the blending tank and means for producing a fine intense sprayof tar or pitch in the gases in the first still.

In testimony whereof I afiix my signature.

GREGORY EDWARD McCliOSKEY.

